Vein filter

ABSTRACT

A vessel filter having a first region and a second region, the filter movable between a collapsed position for delivery to the vessel and an expanded position for placement within the vessel. The first region has a filter portion having a converging region to direct particles toward the center of the filter and includes a plurality of spaced apart filter struts. The struts each have a strut height defined as a distance between a first wall and a second wall. A plurality of hooks are at the second region, the hooks having a vessel penetrating tip and a width greater than the width of the strut from which it extends such that the penetrating tip portion of the hook extends beyond the first wall.

This application is a continuation of prior application Ser. No.12/770,508, filed on Apr. 29, 2010, now U.S. Pat. No. 8,162,972, whichis continuation in part of application Ser. No. 11/978,821, filed Oct.30, 2007 which is a continuation of application Ser. No. 10/889,429filed on Jul. 12, 2004, now U.S. Pat. No. 7,704,266, which claimspriority from provisional application Ser. No. 60/572,274 filed May 18,2004, and which is a continuation in part of application Ser. No.10/805,796 filed on Mar. 22, 2004, now U.S. Pat. No. 7,338,512 whichclaims priority from provisional application Ser. No. 60/538,379, filedJan. 22, 2004, and is a continuation in part of application Ser. No.11/801,547, now U.S. Pat. No. 7,976,562, filed on May 10, 2007, whichclaims priority from provisional application Ser. No. 60/818,202 filedon Jun. 30, 2006 and which is a continuation in part of application Ser.No. 10/889,429 filed on Apr. 27, 2010. The entire contents of each theseapplications are incorporated herein by reference.

BACKGROUND

1. Technical Field

This application relates to a vascular filter and more particularly to avein filter for capturing blood clots within the vessel.

2. Background of Related Art

Passage of blood clots to the lungs is known as pulmonary embolism.These clots typically originate in the veins of the lower limbs and canmigrate through the vascular system to the lungs where they can obstructblood flow and therefore interfere with oxygenation of the blood.Pulmonary embolisms can also cause shock and even death.

In some instances, blood thinning medication, e.g. anticoagulants suchas Heparin, or sodium warfarin can be given to the patient. Thesemedications, however, have limited use since they may not be able to beadministered to patients after surgery or stroke or given to patientswith high risk of internal bleeding. Also, this medication approach isnot always effective in preventing recurring blood clots.

Therefore, surgical methods to reduce the likelihood of such pulmonaryembolisms by actually blocking the blood clot from reaching the lungshave been developed. One surgical method of treatment involved majorsurgery where the size of the vessel lumen was restricted by placementof ligatures or clips around the vein, e.g. the inferior vena cava whichtransports blood from the lower portion of the body to the heart andlungs. This prevented passage of dangerously large blood clots throughthe vein to the lungs. However, this approach is an invasive surgicalprocedure, requiring an abdominal incision and general anesthesia andfrequently causing vessel thrombosis and lower extremity swelling. Also,there is a lengthy patient recovery time and additional hospital andsurgeon expenses associated with this major surgery. In fact,oftentimes, the patients requiring the surgery are unhealthy and themajor surgery and general anesthesia poses a risk in and of itself.

To avoid such invasive surgery, less invasive surgical techniques havebeen developed. These involve the placement of a mechanical barrier inthe inferior vena cava. These barriers are in the form of filters andare typically inserted through either the femoral vein in the patient'sleg or the right jugular vein in the patient's neck or arm under localanesthesia. The filters are then advanced intravascularly to theinferior vena cava where they are expanded to block migration of theblood clots from the lower portion of the body to the heart and lungs.

These prior filters take various forms. One type of filter is composedof coiled wires such as disclosed in U.S. Pat. Nos. 5,893,869 and6,059,825. Another type of filter consists of legs with free ends havinganchors for embedding in the vessel wall to hold the filter. Thesefilters are disclosed, for example, in U.S. Pat. Nos. 4,688,553,4,781,173, 4,832,055, and 5,059,205, 5,984,947 and 6,007,558. Anothertype of filter is disclosed in U.S. Pat. No. 6,214,025 consisting ofwires twisted together to form a cylindrical anchoring portionconforming to the inner vessel wall surface to exert a radial force anda conical filtering portion.

Several factors have to be considered in designing vein filters. Onefactor is that the filter needs to be securely anchored within thevessel wall, while avoiding traumatic engagement and damage to the wallas well as damage to the neighboring abdominal aorta. Another factor isthat the filter must be collapsible to a sufficiently small size to beeasily maneuvered and atraumatically advanced intravascularly to theinferior vena cava or other target vessel. Thirdly, the filter shoulddirect the blood clots to the center of the vessel to improvedissolution of the clot within the vessel by the blood flow.

It would be advantageous to provide a vein filter that satisfies theforegoing parameters. Namely, such vein filter would advantageously havesufficient anchoring force to retain the filter within the vessel whileproviding atraumatic contact with the vessel wall, would have aminimized insertion (collapsed) profile to facilitate delivery throughthe vascular system to the surgical site, and would enable migration ofthe captured blood clots to the center of the vessel. Moreover, it wouldalso be advantageous to provide a filter that could simplify insertionthrough the femoral or the right jugular vein or arm into the inferiorvena cava.

Additionally, the need for a vein filter in many patients is temporary.In these instances it would be advantageous to provide a vein filterthat satisfies the foregoing factors and in addition could be readilyremoved from the patient. Thus, the filter would advantageously strikethe balance of having structure to provide sufficient anchoring whileenabling atraumatic removal from the vessel after a period of time. Itwould further be advantageous if the filter could be removed minimallyinvasively, e.g. intravascularly.

SUMMARY

The present invention provides in one aspect a vessel filter comprisinga first region and a second region, the filter movable between acollapsed position for delivery to the vessel and an expanded positionfor placement within the vessel. The first region has a filter portionhaving a converging region to direct particles toward the center of thefilter and includes a plurality of spaced apart filter struts. Thestruts each have a strut width defined as a distance between a firstwall and a second wall. A plurality of hooks are at the second region,each of the hooks having a vessel penetrating tip, positioned on adistal end portion of the strut, and having a width greater than thewidth of the strut from which it extends such that the penetrating tipportion of the hook extends radially beyond the first wall.

In one embodiment, the hooks have a curved end surface. Preferably, thehook includes a heel extending at an angle to a longitudinal axis of thestrut. In a preferred embodiment, the penetrating tip extends in adirection toward the first region and the heel extends in an oppositedirection.

The filter is preferably formed from a laser cut tube and composed ofshape memory material. Preferably the filter includes a retrieval hookhaving a cutout exposing an internal annular surface, the annularsurface dimensioned to receive a portion of a retrieval sheath.

In some embodiments, connecting filter struts extend at an angle fromthe filter struts to join adjacent filter struts.

In a preferred embodiment, the hooks include a plurality of teethextending in an opposite direction of the penetrating tip. Preferably,the heel extends radially beyond the second wall of the respectivestrut.

In another aspect of the present invention, the vessel filter comprisesa body made from a single tube, the tube cut to create a plurality ofelongated struts forming a filter region and a mounting region ofgreater transverse dimension. The mounting region includes a pluralityof vessel engaging hooks, each of the hooks having a penetrating tippointing in a direction toward the filter region, a plurality of teethfor engaging the vessel, and a heel extending beyond the teeth in adirection opposite the direction of the penetrating tip.

In one embodiment, the penetrating tip extends substantially parallel tothe longitudinal axis of the strut.

In a preferred embodiment, the heel of the hook extends at an angle tothe longitudinal axis of the struts in the mounting region. In oneembodiment, the heel of adjacent vessel engaging hooks terminate axiallyspaced. In one embodiment, the heel of one hook is longitudinallyaligned with the penetrating tip of an adjacent hook.

The present invention provides in another aspect a vessel filtercomprising a first region and a second region, the filter movablebetween a collapsed position for delivery to the vessel and an expandedposition for placement within the vessel. The first region has a filterportion having a converging region to direct particles toward the centerof the filter, the first region including a plurality of spaced apartfilter struts, the struts each having a strut width defined as adistance between a first wall and a second wall. A plurality of hooksare provided at the second region, each hook having a vessel penetratingtip and a heel, the penetrating tip of one hook longitudinally alignedwith a portion of the heel of an adjacent hook.

In one embodiment, the hook has a third and fourth wall and a secondwidth defined between the third and fourth walls, the second widthgreater than the width of the strut from which it extends such that thepenetrating tip portion of the hook extends radially beyond the firstwall. In one embodiment, the heel of the hook extends beyond the secondwall of the strut. The strut can have a reduced diameter areatransitioning into the hook, the reduced area providing a space toaccommodate a heel of an adjacent hook. In one embodiment, thepenetrating tip of the hook points toward the first region. In oneembodiment, the heel has a width less than the width of the respectivestrut. The hook can have a heel that extends at an angle to thelongitudinal axis.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiment(s) of the present disclosure are described hereinwith reference to the drawings wherein:

FIG. 1 is a perspective view of a first embodiment of the vein filter ofthe present invention in the collapsed configuration;

FIG. 2 is an enlarged side view of a portion of the vein filter of FIG.1;

FIG. 3 is a perspective view of the vein filter of FIG. 1 in an expandedconfiguration;

FIG. 4A is a side view of the vein filter of FIG. 1 in another expandedconfiguration;

FIG. 4B is a front view of the vein filter of FIG. 4 in the expandedconfiguration;

FIG. 5 is a side view of the vein filter of FIG. 3 in the expandedconfiguration;

FIG. 6A is a close up view of a portion of the struts showing oneembodiment of anchoring elements having pointed ends;

FIG. 6B is a close up view of a portion of one of the struts showinganother embodiment of anchoring elements in the form of hemisphericalcutouts;

FIG. 7 is a perspective view of an alternate embodiment of the veinfilter of the present invention shown in the expanded configuration;

FIG. 8 is a side view of the vein filter of FIG. 7;

FIG. 9 is a side view of a portion of the vein filter of FIG. 7 shown inthe collapsed configuration;

FIG. 10 is a perspective view of another alternate embodiment of thevein filter of the present invention shown in the expandedconfiguration;

FIG. 11A is a perspective view of yet another alternate embodiment ofthe vein filter of the present invention shown in the expandedconfiguration;

FIG. 11B is a view similar to FIG. 11A showing an alternate embodimentof the hooks;

FIG. 11C is a view similar to FIG. 11A showing another alternateembodiment of the hooks;

FIG. 11D is a view similar to FIG. 11A showing yet another alternateembodiment of the filter of the present invention;

FIG. 11E is a perspective view of the filter of FIG. 11D in thecollapsed position;

FIG. 11F is an enlarged view of the retention hooks of FIG. 11D;

FIG. 11G is a perspective view of an alternate embodiment of the filterof FIG. 7 having the retention hooks of FIG. 11D;

FIG. 11H is an enlarged view of the retention hooks of FIG. 11G in thecollapsed position;

FIG. 12A is a close up perspective view of an alternate embodiment of anend of the filter having a series of cutouts to receive a retrievalsnare;

FIG. 12B is a close up perspective view of an alternate embodiment of anend of the filter having cutouts to receive a retrieval snare;

FIG. 12C is a side view of the embodiment of FIG. 12B showing aretrieval snare placed in one of the cutouts between the coils;

FIG. 13A is a close up perspective view of another alternate embodimentof an end of the filter having a hook to receive a retrieval snare;

FIG. 13B is a perspective view of an end of the filter illustratinganother alternate embodiment of the hook to receive a retrieval snare;

FIGS. 13C and 13D are perspective and top views, respectively, of analternate embodiment of the hook to receive a retrieval snare;

FIG. 13E is a top view of an alternate embodiment of the hook of FIG.13C;

FIGS. 13F and 13G are perspective and side views, respectively, ofanother alternate embodiment of the hook to receive a retrieval snare;

FIGS. 13H-13J are side views showing the method steps for engaging thehook of FIG. 13F for removing the filter utilizing a retrieval snarewhen the snare approaches from one orientation;

FIGS. 13K-13N are side views showing the method steps for engaging thehook of FIG. 13F for removing the filter utilizing a retrieval snarewhen the snare approaches from an orientation opposite the orientationof FIG. 13H;

FIGS. 14, 15 and 16 illustrate delivery and placement of the vesselfilter of FIG. 1 in the inferior vena cava wherein FIG. 14 illustratesinitial insertion of the delivery sheath through the femoral vein, FIG.15 illustrates the delivery sheath being advanced toward the inferiorvena cava just below (upstream) the juncture of the renal arteries; andFIG. 16 illustrates the delivery sheath fully withdrawn to place thefilter in the expanded placement configuration in the inferior venacava;

FIG. 17 is a perspective view of one embodiment of a delivery system forthe vein filter;

FIG. 18 is an exploded view of the delivery system of FIG. 17;

FIG. 19 is a cross-sectional view showing the engagement of theinterlocking rails of the cartridge with the hub;

FIG. 20A is a perspective view of an alternate embodiment of the filterof the present invention having interconnecting struts in the filterportion, the filter shown in the expanded configuration;

FIG. 20B is a front view of the filter of FIG. 20A;

FIG. 20C is a side view of the filter of FIG. 20A;

FIG. 20D is a perspective view of the filter of FIG. 20A shown in thecollapsed configuration;

FIG. 20E is an enlarged view of an end portion of the filter of FIG. 20Dshowing the retention hooks;

FIG. 20F is an enlarged developed view of the end portion of the filterof FIG. 20D showing the axial relationship of the retention hooks;

FIG. 21 is a perspective view of another alternate embodiment of thefilter having interconnecting struts in the filter portion;

FIG. 22A is a perspective view of another alternate embodiment of thefilter of the present invention having interconnecting struts in thefilter portion and in the mounting portion;

FIGS. 22B and 22C are front and side views, respectively of the filterof FIG. 22A;

FIG. 22D is a perspective view of the filter of FIG. 22A shown in thecollapsed configuration;

FIG. 22E is an enlarged view of an end region of the filter of FIG. 22Din the collapsed configuration;

FIG. 23 is a perspective view of another alternate embodiment of thevein filter of the present invention in the collapsed configuration fordelivery;

FIG. 24 is a close up perspective view of the retention hooks of thefilter of FIG. 23 in the collapsed position;

FIG. 25 is a perspective view of the vein filter of FIG. 23 in theexpanded configuration;

FIG. 26 is a front view of the filter of FIG. 25;

FIG. 27 is a side view of the filter of FIG. 25 showing the axialspacing of the retention hooks; and

FIG. 28 is an enlarged developed view of the end portion of the filterof FIG. 27.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Turning now to the drawings, wherein like reference numerals identifysimilar or like components throughout the several views, variousembodiment of the vein filter of the present invention are described forplacement within the inferior vena cava to capture blood clots or otherparticles which could otherwise pass to the lungs.

The filter is movable from a low profile collapsed configuration tofacilitate insertion through the delivery sheath to a larger expandedplacement configuration to enable atraumatic engagement with the vesselwalls to secure (mount) the filter within the inferior vena cava. Thefilter is preferably substantially bell-shaped and preferably has aflared or mounting region (portion/section) and a filtering region(portion/section). As described in more detail below, the filteringportion has inwardly directed struts, terminating in a convergingregion, thereby directing particles toward the central axis of thefilter. By directing the particles to the center, they will be exposedto greater blood flow which improves dissolution of the particles. Theother portion increases in transverse dimension to form a flared region.The flare provides less contact area than a straight region, resultingin less tissue ingrowth to facilitate removal of the filter if desired.The flare also reduces the chance of vessel distortion if inserted intoa curved vena cava.

Turning now to details of the filter of the present invention and withinitial reference to FIGS. 1 and 2, the filter is designated generallyby reference numeral 10 and is shown in a collapsed configuration fordelivery. Filter 10 is preferably formed from a single tube 11. In apreferred embodiment, the filter 10 is composed of shape memorymaterial, such as Nitinol, a nickel titanium alloy, or elgiloy, however,other materials such as stainless steel are also contemplated. Aplurality of cutouts 12 are formed in the filter 10, preferably by lasercutting although other techniques are contemplated. In the illustratedembodiment, six elongated cutouts are formed, creating six strips orstruts 14 of substantially uniform width separated by the cutouts 12 andextending from tubular portion 18.

The collapsed configuration of filter 10 reduces the overall profile tofacilitate delivery to the site. The diameter or transverse dimension offilter 10 in the collapsed configuration is represented by reference D1and preferably is about 2 mm and more preferably about 1.7 mm. Otherdimensions are also contemplated. The diameter or transverse dimensionsof the filter in the expanded placement configurations (e.g. FIGS. 4Aand 5) is greater than the diameter or transverse dimension D1 in thecollapsed (delivery) configuration. The filter is thus preferablydimensioned for insertion through a 6 French delivery system and througha 6 French catheter.

FIGS. 3-5 illustrate the expanded placement configuration of the filter10. Filter 10 is generally bell-shaped in configuration. Filter 10 has aflared region 17 and a converging region 21 at the filtering section 19.The transverse dimension of the filter at flared (or mounting/anchoring)region 17 is thus greater than the transverse dimension at filteringsection 19. In larger vessels, the filter can expand to a diameter D2shown in FIG. 5. In smaller vessels, the filter expands to a smallerdiameter, e.g. D3, shown in FIG. 4. Diameters (or transverse dimensions)D2-D3 preferably range from about 18 mm to about 32 mm, depending on theinternal diameter of the vessel wall as will be explained in more detailbelow. Other dimensions are also contemplated.

The elongated struts 14 are spaced apart as shown and extend at an angleaway from the longitudinal axis L of filter 10 in region 17 to provide aflare. Preferably, this angle or taper is about 10°, although otherdimensions are contemplated. In the filtering region 19, beginning at anintermediate portion of the filter (the transition between the first andsecond regions 17, 19) the struts 14 curve or bend inwardly (region 23)toward the longitudinal axis and then extend inwardly at an angle to thetubular portion 18, thereby forming an angle with the longitudinal axis.In the illustrated embodiment, when expanded, the six struts 14 areshown spaced approximately 60 degrees apart. It is also contemplatedthat a fewer or greater number of struts could be provided and spacingother than 60 degrees be provided.

In the expanded placement configuration, a portion of the each elongatedstrut 14 has an outer surface 20 for engagement with the vessel wall toretain the filter 10 in position in the vessel. This region is angledwith respect to the longitudinal axis. The outer surface 20 of struts 14could be roughened to enhance engagement. Alternatively, a plurality ofatraumatic tabs, barbs or other penetrating members can extend from theouter surface 20 of the struts 14 to engage the vessel wall to retainthe filter. FIGS. 6A and 6B show examples of such retention features. InFIG. 6B, the filter has a series of hemispherical cutouts 152 formedalong the length of the struts 154 forming pointed edges 156 to engagethe vessel wall. The cutouts 152 can be formed along the length of thestrut 154 or alternatively be formed only along a portion of the length.The cutouts can also be formed on fewer than all the struts.

In the embodiment of FIG. 6A, the filter has anchoring elements 162formed by cutouts 163 at the ends of the struts 164. Anchoring elements162 have pointed ends 165. In the collapsed configuration the anchoringelements 162 and their pointed ends 165 are aligned with the struts 164,substantially parallel with the longitudinal axis of the filter tomaintain a reduced profile. When the filter moves to the expandedconfiguration, the pointed ends 165 face outwardly as shown in FIG. 6A.Anchoring elements 162 can be placed in the end regions of the strut orin other locations. The anchoring elements can also be placed in theopposite direction shown.

In the embodiment of FIG. 11A, the struts 174 of filter 170 terminate inhooks 172 which extend substantially perpendicular from the strut. Hooksextend from the substantially V-shaped region 179 formed by the joiningof connecting struts 174 a, 174 b. In the alternate embodiment of FIG.11C, struts 184 of filter 180 also terminate in substantiallyperpendicular hooks 182, however this arrangement is achieved bytorquing the connecting struts 184 a, 184 b at the curved region 185 sothe hooks bend out of the plane. As shown, hooks 182 extend fromV-shaped region 189 formed by the connecting struts 184 a, 184 b. In thealternate embodiment of FIG. 11B, the hooks 192 of filter 190 (havingstruts 194) lie in the plane of the connecting struts 194 a, 194 b,flush with the width surface “w” of the V-shaped region 199 ofconnecting struts 194 a, 194 b.

In the alternate embodiment of FIGS. 11D-11F, the hooks 302 lie in thesame plane as the connecting struts 304 a, 304B of struts 310 as in FIG.11B; however the hooks of filter 301 are of two different sizes. Morespecifically, a first set of hooks 302 a is larger than a second set ofhooks 302 b. Preferably when formed in a laser cut tube, hooks 302 a areformed so that they occupy a region equivalent to the transversedimension of two adjacent struts. For example, in the collapsedconfiguration, hook 302 a occupies a region (dimension) of fourconnecting struts while smaller hook 302 b would only occupy the region(dimension) of two connecting struts. Smaller hooks 302 b are spacedaxially inwardly with respect to larger hooks 302 a to minimize thecollapsed profile (transverse dimension) of the filter when collapsedfor insertion. In this preferred embodiment, smaller hooks 302 b occupythe space created by the larger hooks 302 a so they can be considered asnesting within larger hooks 306 a. Stated another way, each hook 302 bhas an outer surface 307 which conforms (follows the contour) to aninner surface 309 of a hook 306 a. The penetrating tips 306 a, 306 b inhooks 302 a, 302 b, respectively, penetrate the tissue to retain thefilter, preferably temporarily.

The aforedescribed hooks 172, 182, 192, 302 (as well as the hooksdescribed below) can be used with any of the disclosed embodiments (seee.g. FIG. 11G). Such hooks can also be formed or placed on fewer thanall the struts.

Referring back to FIGS. 3-5, the filter portion of filter 10 will now bediscussed. As noted above, the filtering section of filter 10 at a firstend of the filter is designated generally by reference numeral 19 andincludes the converging region 21. Filtering section 19 extends from theflared region 17, and extends toward the central longitudinal axis L ofthe filter 10 and converges at portion 32 into tubular portion 18. Atthe transition region between the filtering and flared regions 19, 17,struts 14 bend inwardly (region 23), then extend radially inwardlytoward the tubular portion 18, and transition to the tubular portion 18.The tubular portion 18 and converging region 19 of the filter 10 arespaced both axially outwardly and radially inwardly from the bendregions 23 of the strut 14. (Axially outwardly is represented by arrow“a” and radially inwardly is represented by arrow “b” in FIG. 4A). Thefilter is designed to direct particles to the center of the filter andvessel. (Trapping the particles at the center rather than the edges ofthe filter is more desirable because there is less blood flow at theedges of the vessel and greater blood flow at the center to betterdissolve the particles.) For clarity, not all of these sections of eachstrut 14 are labeled in the drawings, it being understood that thenon-labeled struts can have the same configurations.

Turning now to the flared or mounting (anchoring) region 17, each strut14 is divided into two connecting strut portions 14 a, 14 b. Preferably,each strut portion 14 a, 14 b is about one half the width of theundivided strut 14, although other widths are contemplated. The strutportions 14 a, 14 b of each divided strut 14 extend in oppositedirections and include a curved region 25 as the strut portions 14 a, 14b each extend toward respective strut portion 14 a or 14 b of anadjacent strut. That is, strut portions 14 a, 14 b form connectingportions to connect adjacent struts 14 as connecting strut 14 a of onestrut is connected to connecting strut 14 b of an adjacent strut.Connecting strut portion 14 a on one strut and portion 14 b of anotherstrut converge at end region 29 of the filter and form a substantiallyV-shaped region. Six such V-shaped end portions are preferably formed,each portion connecting adjacent struts. Note that although all sixstruts 14 are shown interconnected, it is also contemplated that fewerthan all the struts can be interconnected.

Note the designations of longitudinal, angled, curved, bowed, connected,joined, interconnected, connecting strut, etc. in the illustratedembodiments refer to the same integral strut and are divided into suchregions for ease of understanding.

It should be understood that the elongated struts 14 bend as they movefrom their collapsed position to their expanded placement configuration.Therefore, stated another away, the filter 10 can be viewed as having afiltering section 19 at a first end extending from the tubular portion18. As viewed, each of the struts 14 emerges from the tubular portion 18at an angle that extends outwardly away from the center to transition tocurved portions 23. The curved portions 23 extend outwardly away fromthe longitudinal axis forming a flare or region of progressivelyincreasing transverse dimension. In this flared region 17, near a secondend of the filter (opposite the end containing tubular portion 18), thestruts 14 are interconnected by connecting struts 14 a, 14 b that curveinwardly toward the connecting strut 14 a or 14 b of an adjacent strutto form a substantially V-shaped end portion.

In the placement (expanded) configuration, the filter 10 moves towardsits memorized position and the extent it returns to its fully memorizedposition will be dependent on the size of the vessel in which the filter10 is inserted. (The larger the vessel, the closer the filter comes toreturning to it's fully memorized position). This can be understood bycomparing FIGS. 4A and 5 which illustrate by way of example two possibleexpanded dimensions of the filter; FIG. 4A showing expansion to asmaller dimension occurring in smaller diameter vessels and FIG. 5showing expansion to a larger dimension occurring in larger diametervessels.

To enable movement between an expanded and collapsed configuration, thefilter tube of the embodiments described herein is preferably made ofshape memory metal material, such as Nitinol, a nickel titanium alloy.The memorized configuration of the filter 10 is shown in FIG. 1. Tofacilitate passage of the filter 10 through the lumen of the deliverysheath 100 (shown in FIG. 14 in conjunction with the method ofinsertion) and into the vessel, cold saline can be injected into thedelivery sheath or catheter 100 and around the filter 10 in itscollapsed position within the delivery sheath 100. This shape memorymaterial characteristically exhibits rigidity in the austenitic stateand more flexibility in the martensitic state. The cold saline maintainsthe temperature dependent filter 10 in a relatively softer condition asit is in the martensitic state within the sheath. This facilitates theexit of filter 10 from the sheath 100 as frictional contact between thefilter 10 and the inner surface of the sheath would otherwise occur ifthe filter was maintained in a rigid, i.e. austenitic, condition.

Once ejected from the delivery sheath or catheter 100, the filter is nolonger cooled and is exposed to the warmer body temperature, whichcauses the filter 10 to return towards its austenitic memorizedconfiguration.

The filter 10 (and other filters described herein) can be insertedthrough the jugular vein in the neck of the patient or through thefemoral vein in the leg of the patient or the arm. The filters can alsobe placed in the superior vena cava.

FIGS. 14-16 illustrate delivery and placement of the filter 10, by wayof example, in the inferior vena cava. Delivery catheter 100 is insertedthrough the femoral vein “f” and advanced through the iliac arteriesinto the inferior vena cava. Delivery catheter would be withdrawn oncethe tip of the sheath is adjacent the structure so that withdrawal ofthe sheath would place the filter in the desired location of FIG. 16.Tubing 104 and valve assembly 106 enable saline injection. Deliverycatheter 100 is withdrawn to enable filter 10 to be warmed by bodytemperature to transition to the expanded placement configuration. Theother filters described herein could be inserted in the same manner.Note it is implanted in the orientation such that filter section 19 isdownstream of the flared section 17. This enables blood clots or otherparticles to be directed to the center of the filter section by theangled struts. Thus the direction of insertion, e.g. upstream ordownstream direction, will determine how the filter is to be positionedin the delivery catheter.

In an alternate embodiment of the filter, the strut width can vary. Forexample, the struts can be wider at the flared region than at thefiltering portion. This is preferably achieved by removing material tocreate the thinner portions. These thinner portions increase theflexibility of the filter for forming the angled and curved portionsupon deployment. Alternatively, the filter can have struts which arethinner, rather than wider, at the flared region, than at the angled andcurved regions of the filtering portion. This would provide morestability at the curved regions. The adjustment of the widths isdesigned to strike a balance between stability and flexibility of thevarious regions of the filter. Thus, other width variations arecontemplated such as making multiple width changes within each strutand/or in different struts.

FIGS. 7-9 illustrate an alternate embodiment of the filter, designatedby reference numeral 110. Filter 110 is similar to filter 10 except forend region 121. That is, like filter 10, filter 110 has a filteringregion 119 which extends from the flared (anchoring/mounting) region117, and extends toward the central longitudinal axis L of the filter110 and converges at portion 132 into tubular portion 118. Struts 114bend inwardly toward the longitudinal axis of the filter 10 at region123. For clarity, not all of these sections of each strut 114 arelabeled in the drawing, it being understood that the non-labeled strutscan have the same configurations. The flared region 117 as in filter 10is of an angle preferably about 8 degrees although other angles arecontemplated.

The end region 121 of filter 110 where the struts 114 interconnectdiffers from filter 10. In filter 110, the struts 114 are interconnectedby connecting strut portions 114 a, 114 b that curve outwardly away fromthe central axis and then inwardly toward each other to form asubstantially V-shaped end portion 127. At the outward curved or bowedportion 124, the connecting struts are joined to connecting struts ofadjacent struts 114 (region 125). Thus, a closed geometric shape 133 isformed as shown. The closed shape as shown is substantially oval inconfiguration, although other shapes are contemplated. Six such closedgeometric shapes are preferably formed, each connecting adjacent struts,although fewer closed shapes are contemplated if fewer than all thestruts are interconnected. Also, the length of the region 125 where thestruts are joined can be shorter or longer than that shown, therebychanging the configuration of the closed geometric shape (e.g. making itlonger or shorter).

Stated in other words, each strut 114 divides into two connecting strutportions 114 a, 114 b which initially extend outwardly from each other.As each strut extends outwardly, the strut portion 114 a joins the strutportion 114 b of an adjacent strut at region 125. After this joinedregion 125, the strut portions 114 a and 114 b which emanate from thesame strut extend inwardly towards each other and are joined at theirends into a substantially V-shaped end, designated by reference numeral127.

The collapsed configuration of filter 110 is shown in FIG. 9 withcutouts 112 forming six struts 114. Regions 113 illustrate where struts114 divide.

In the alternate embodiment of FIG. 10, filter 150 resembles filter 10of FIG. 1 except for the additional connecting struts or ribs 152. Theseribs increase the stability of the filter 150. As shown, the two ribs152 extend from adjacent struts 154 and curve inwardly towards eachother and are joined at region 156 (forming a V-like connection). Theribs 152 can be arranged so they are axially aligned as in FIG. 10 oralternatively can be staggered i.e. spaced axially (not shown). Also,the ribs can be placed between fewer than all the struts and the ribscan be utilized with any of the foregoing embodiments. Note that theribs are preferably integrally formed with the filter, formed by thelaser cutting process mentioned above; however, alternatively the ribscan be attached to the struts. Struts 154 divide into connecting struts154 a, 154 b in the embodiment of FIG. 1.

FIGS. 11G and 11H illustrate an alternate embodiment of the filter ofFIG. 7 having the hooks of filter 301 of FIG. 11D. Filter 350, likefilter 110, has struts 354 which are interconnected by connecting strutportions 354 a, 354 b that curve outwardly then inwardly toward eachother to form V-shaped portions 357, terminating in hooks 356. As inFIG. 11D, large hooks 356 a alternate with axially offset smaller hooks356 b and are identical to hooks 306 a, 306 b of FIG. 11D.

In another embodiment, the ribs could curve radially outward near theirtips, thus contacting the vessel wall and acting as a retainingmechanism.

FIG. 20A illustrates an alternate embodiment of the filter of thepresent invention. In this embodiment, the struts are interconnected atthe filtering region rather than at the flared mounting (anchoring)region. This creates closed geometric shapes at the filtering region toenhance the clot capturing capability of the filter. Also, by providingthe interconnection more forward (downstream) in the filter, i.e. in thefiltering region (filtration zone), linear movement of the filter isfacilitated to enhance removal of the filter.

Turning first to FIGS. 20A and 20C, bell-shaped filter 700 has afiltering region 719 and a flared anchoring (mounting) region 721 ofgreater transverse dimension. Flared region 721 is preferably at anangle of about 8 degrees to about 14 degrees with respect to thelongitudinal axis of the filter, although other angles are contemplated.In this flared region 721, the transverse dimension increases towardsthe anchoring end of the filter 700 so that as in the other embodimentsdisclosed herein, the terminal end of the filter at region 719 has asmaller transverse dimension than at the opposing terminal end at region721. The filtering region 719 extends from the flared region 721 towardthe longitudinal axis of the filter 700 and converges at portion 732into tubular portion 718 at the filter end portion of filter 700.

Filtering region 719 has six struts 714 curving outwardly from tubularportion 718. Each filter strut or strut portion 714 extends radiallyfrom tubular portion 718 and divides into two connecting filter strutsor strut portions 714 a, 714 b (preferably of equal width) that angleway from each other (in different directions) to extend to theconnecting strut portion of an adjacent strut 714. Thus, connectingstrut portion 714 a of one strut 714 interconnects with the connectingstrut portion 714 b of an adjacent strut at joining region 714 d. Thisforms closed geometric shapes 725, preferably substantially diamondshaped in configuration. For clarity, not all of the identical parts arelabeled in the drawing. In the illustrated embodiment, preferably sixstruts are provided forming twelve interconnecting struts, however adifferent number of struts and closed geometric shapes can be provided.Also, fewer than all of the struts could be interconnected. Althoughpreferably the struts 714 divide into connecting struts 714 a, 714 b ofhalf the width, other dimensions are contemplated.

After convergence of strut portions 714 a, 714 b at joining region 714d, it transitions into elongated mounting strut portions 714 c whichform flared mounting or anchoring region 721. The length of the strutportions 714 c in the anchoring region 721 can vary, withincreased/decreased length increasing the flexibility/rigidity of thestruts. The thickness of the strut portions can also vary to affectflexibility/rigidity.

In one embodiment, the strut portions 714 c terminate in hooks 740 a,740 b similar to hooks 302 a, 302 b of FIG. 11D. That is, hooks 740 aand 740 b lie in the plane of the struts 714 c and hooks 740 a arelarger than hooks 740 b, formed so they occupy a region equivalent tothe transverse dimension of two adjacent struts. Smaller hooks 740 bnest within larger hooks 740 a as described above in conjunction withhooks 302 a, 302 b. Note that smaller hooks 740 b are spaced axially(inwardly) of hooks 740 a as well as spaced axially with respect to eachother as represented by the arrows in FIG. 20F designating the threedifferent distances E1, E2 and E3 in the developed view, presented forease of understanding since the hooks are formed from a tube. Other hookdesigns could alternatively be provided, including the various hookembodiments described herein.

The tubular portion 718 is preferably in the form of a retrieval hook asdescribed herein with respect to the other embodiments, and preferablyin the form of retrieval hook 290 of FIG. 13F. Other retrieval structurecan also be utilized.

In the alternate embodiment of FIG. 21, the filter is designatedgenerally by reference numeral 800 and has a filtering region 819 and aflared anchoring (mounting) region 821. The filter 800 differs fromfilter 700 in the additional joining regions of the connecting struts.More specifically, filter struts 814 extend radially from tubularportion 818, in a similar manner as struts 714 of FIG. 20A. Struts 814divide into connecting struts or strut portions 814 a, 814 b, extendingin different directions, and then join at first joining regions 814 c toa connecting strut of an adjacent strut 814. Emanating from joiningregions 814 c, connecting struts or strut portions 814 f, 814 g, extendin different directions, away from each other, to connect to anotheradjacent strut 814 f or 814 g at second joining regions 814 d. Atregions 814 d, the mounting struts or strut portions 814 h extendlongitudinally to form the flared mounting or anchoring region 821. Theinterconnecting struts preferably form a first set of substantiallydiamond shaped closed geometric shapes 830 as shown and a second set ofsubstantially hexagonal shaped closed geometric shapes 832. Other shapesare contemplated as are a different number of struts 814,interconnecting struts, and closed geometric shapes. For clarity, notall identical parts are labeled in the drawings.

At the terminal ends of the struts 814 at the mounting portion 821,retention hooks are provided. Hooks 840 a, 840 b as shown are identicalto hooks 740 a, 740 b of FIG. 20. Retrieval hook 850 at the tubular endportion 818 of the filtering end portion of filter 800 is preferablyidentical to retrieval hook 750 of filter 700. Other hook designs andretrieval structure could alternatively be utilized.

FIGS. 23-28 illustrate an alternate embodiment of the filter of thepresent invention, designated generally by reference numeral 1010.Filter 1010 is substantially identical to filter 700 of FIGS. 20A-20Eexcept for the retention hooks. Filter 1010 has struts interconnected inthe filtering region and not in the flared mounting (anchoring) regionas in filter 700. This creates closed geometric shapes at the filteringregion to enhance the clot capturing capability of the filter. Themounting region is devoid of such closed geometric shapes as it isdevoid of interconnecting or connecting struts. This facilitatesremoval.

Filter 1010 is substantially bell shaped and has a filtering region 1012and a flared anchoring (mounting) region 1024 of greater transversedimension. Flared region 1024 is preferably at an angle of about 8degrees with respect to the longitudinal axis of the filter, althoughother angles are contemplated. In this flared region 1024, thetransverse dimension increases towards the anchoring end of the filter1010 so that as in the other embodiments disclosed herein, the terminalend of the filter at region 1019 has a smaller transverse dimension thanat the opposing terminal end at region 1021. The filtering region 1012extends from the flared region 1024 toward the longitudinal axis of thefilter 1010 and converges at portion 1022 into tubular portion 1018 atthe filter end portion of filter 1010.

Filtering region 1019 preferably has six struts 1014 curving outwardlyfrom tubular portion 1018. Each filter strut or strut portion 1014extends radially from tubular portion 1018 and divides into twoconnecting (interconnecting) filter struts or strut portions 1014 a,1014 b (preferably of equal width) that angle way from each other (indifferent directions) to extend to the connecting strut portion of anadjacent strut 1014. Thus, connecting strut portion 1014 a of one strut1014 interconnects with the connecting strut portion 1014 b of anadjacent strut at joining region 1014 d. This forms closed geometricshapes 1025, preferably substantially diamond shaped in configuration,although other shapes are contemplated. For clarity, not all of theidentical parts are labeled in the drawing. In the illustratedembodiment, preferably six struts are provided forming twelveinterconnecting struts, however a different number of struts and closedgeometric shapes can be provided. Also, fewer than all of the strutscould be interconnected. Although preferably the struts 1014 divide intoconnecting struts 1014 a, 1014 b of half the width, other dimensions arecontemplated.

After convergence of strut portions 1014 a, 1014 b at joining region1014 d, it transitions into elongated mounting strut portions 1014 cwhich form flared mounting or anchoring region 1024. The length of thestrut portions 1014 c in the anchoring region 1024 can vary, withincreased/decreased length increasing the flexibility/rigidity of thestruts. The thickness of the strut portions can also vary to affectflexibility/rigidity.

Preferably, the strut portions 1014 c terminate in hook portions 1030.Hook portions 1030 in this embodiment are preferably of substantiallythe same size. In the preferred embodiment, the hook portions or thestruts from which they extend have different lengths so that thedistalmost end of the hook portions 1030 terminate at different axialpositions. Stated another way, the hooks are staggered in an axialdirection so the struts terminate at different points. FIG. 28illustrates the six different distances, in the developed view,presented for ease of understanding since the hooks are formed from atube.

Hook portions 1030 lie in the plane of a distal portion 1014 d of thestruts 1014 c. That is, the distal portion 1014 d of the strut 1014 ctwists out of the plane of the remaining portion of the strut, with thehooks lying in the plane of the distal portion.

Hook portions 1030 includes a hook 1032 having a penetrating tip 1034preferably pointing toward a proximal portion (filter region) of thefilter 1010. A top wall 1036 of the hook 1032 has a slight step 1038.The penetrating tip 1034 extends about a curved wall 1039. Thepenetrating tip 1034 in the illustrated embodiment extends substantiallyparallel to a longitudinal axis L1 of the struts portion 1050. Oppositethe curved wall 1039 on hook 1032 are a plurality of teeth 1040, withpoints or edges facing in a distal direction, opposite the direction ofthe penetrating tip 1034. Teeth 1040 engage the vessel wall to provideadditional retention to prevent movement of the implanted filter in thecaudal direction. A heel 1044 is formed on a distal end of the hookportion 1030, terminating in a curved surface 1046 and extendingdistally beyond the hook 1032. Heel 1044 extends past the hook 1032 tofunction as a stop to prevent the filter strut portions from goingthrough the vessel wall. Hook portion 1030 also has a reduced widthdimension Z1 which transition from the strut 1014 d to the hook 1032.For clarity, only some of the hooks and hook portions are labeled inFIG. 28.

Preferably hook portions 1030 somewhat nest within an adjacent hookportion. More specifically, the strut of portion 1030 has a reduced area1049 (with width dimension Z1) which forms a gap 1045 to receive aportion of heel 1044 of an adjacent hook portion 1030. In thisconfiguration, a portion of the heel 1044 of the hook portion 1030 is ingeneral longitudinal alignment with a penetrating tip 1034 of anadjacent hook as described below.

The strut 1014 d at the reduced area portion 1049 has a first wall 1052and a second wall 1054 forming a width Z1 defined as the distance orspace between the walls 1052, 1054. The strut 1014 d adjacent thereduced area 1049 has a first wall 1056 and a second wall 1058, forminga width Z2, defined as the distance or space between walls 1056, 1058.Line S1 represents this first wall 1056 of strut 1014 d. As can beappreciated, the hook 1032 has a height Z3 greater than height Z2 suchthat it extends widthwise beyond the height of the first wall 1052. Inother words, the penetrating tip 1034 extends radially beyond the LineS1, illustrated by line S2 (extrapolated from the perpetrating tip1034). By way of example, width Z1 could be between about 0.013 inchesto about 0.019 inches, and preferably about 0.016 inches, width Z2 couldbe between about 0.025 inches to about 0.035 inches, and preferablyabout 0.030 inches, width Z3 could be about 0.035 inches to about 0.045inches, and preferably about 0.040 inches, and width Z4 at the heel 1044could be between about 0.011 inches to about 0.017 inches, andpreferably about 0.014 inches. It should be understood that otherdimensions are also contemplated.

Line S3 represents the second wall 1058 extrapolated in a proximaldirection. As can be appreciated, the heel 1044 extends widthwise beyondthe line S3 and width of the second wall 1054. Wall 1058 also includes aslight indentation 1055 to accommodate the penetrating tip portion 1034of the adjacent hook 1032.

The tubular portion 1018 is preferably in the form of a retrieval hookas described herein with respect to the other embodiments, andpreferably in the form of retrieval hook 290 of FIG. 13F. Otherretrieval structure can also be utilized.

FIG. 22 illustrates an alternate embodiment of the filter of the presentinvention. In this embodiment, the struts are interconnected at thefiltering region (filtration zone) and at the flared mounting(anchoring) region. These interconnecting struts at the filtering regionenhance the clot capturing capability of the filter. The interconnectionat the mounting region enhances the stability of the filter and thevessel retention capability by reducing the flexibility of the struts.

Referring to FIGS. 22A and 22C, bell-shaped filter 900 has a filteringregion 919 and a flared anchoring (mounting) region 921 of greatertransverse dimension. Flared region 921 is preferably at an angle ofabout 8 degrees with respect to the longitudinal axis of the filter,although other angles are contemplated. In this flared region 921, thetransverse dimension increases towards the anchoring end of the filter900 so the terminal end of the filter at region 919 has a smallertransverse dimension than the opposing terminal end at region 921. Thefiltering region 919 extends from the flared region 921 toward thelongitudinal axis of the filter 900 and converges at portion 932 intotubular portion 918 at the filter end portion of filter 900.

Filtering region 919 has six struts 914 curving outwardly from tubularportion 918. Each elongated filter strut or strut portion 914 extendsradially from tubular portion 918 and divides into two connecting filterstruts or strut portions 914 a, 914 b (preferably of equal width) thatangle way from each other (in different directions) to extend to theconnecting strut portion of an adjacent strut 914. Thus, connectingstrut portion 914 a of one strut 914 interconnects with the connectingstrut portion 914 b of an adjacent strut at joining region 914 d. Thisforms closed geometric shapes 925, preferably substantially diamondshaped in configuration. For clarity, not all of the identical parts arelabeled in the drawing. In the illustrated embodiment, preferably sixstruts are provided forming twelve interconnecting struts in thefiltering region, however a different number of struts and closedgeometric shapes can be provided. Also, fewer than all of the strutscould be interconnected. Although the struts 914 can divide intoconnecting struts 914 a, 914 b of half the width, other dimensions arecontemplated such as equal to the width.

After convergence of strut portions 914 a, 914 b at joining region 914d, it transitions into elongated mounting strut portions 914 c whichform flared mounting or anchoring region 921. The length of the mountingstrut portions 914 c in the anchoring region 921 can vary, withincreased/decreased length increasing the flexibility/rigidity of thestruts. The thickness of the strut portions can also vary to affectflexibility/rigidity. Each strut 914 c divides into two connectingmounting strut portions 914 e, 914 f. Each strut portion 914 e, 914 fcan be one half the width of the undivided strut 14, although otherwidths are contemplated such as equal to the width. The strut portions914 e, 914 f of each divided strut 914 c extend in opposite directionsand include a curved region as the strut portions 914 e, 914 f eachextend toward respective strut portion 914 e or 914 f of an adjacentstrut. That is, strut portions 914 e, 914 f form connecting portions toconnect adjacent struts 914 c as connecting strut 914 e of one strut isconnected to connecting strut 914 f of an adjacent strut. Connectingstrut portion 914 e on one strut and portion 914 f of another strutconverge at end (joining) region 929, as closed geometric shapes 935 areformed. End region 929 has an elongated region (or hook strut) 931 andpreferably terminates in hooks described below. Note that although allsix mounting struts 914 are shown interconnected, it is alsocontemplated that fewer than all the struts can be interconnected.

Thus, as can be appreciated, the elongated struts have a first angledregion of interconnecting (connecting) struts 914 a, 914 b in thefiltering region 919 and a second angled region of interconnecting(connecting) struts 914 e, 914 f in the mounting region 921. The regionof the interconnecting struts in the first region (the filtering region)has a transverse dimension less than the transverse dimension of theregion having the interconnecting struts in the mounting region.

In the embodiment of FIG. 22, the filter strut portions and mountingstrut portions each divide into connecting struts of half the width. Inan alternate embodiment, the filter struts and mounting struts are alsobifurcated, however the width of the connecting strut is increased so itis greater than one half the width of the struts and can for instance beequal to the width of the strut. Such bifurcation with increased widthis also applicable to the other embodiments of the filter describedherein. Bifurcation with decreased width is also contemplated.

Preferably, the strut portions 914 c terminate in hooks 940 a, 940 bsimilar to hooks 302 a, 302 b of FIG. 11D. That is, hooks 940 a and 940b lie in the plane of the struts 914 and hooks 940 a are larger thanhooks 940 b, formed so they occupy a region equivalent to the transversedimension of two adjacent struts. Smaller hooks 940 b nest within largerhooks 940 a in the same manner as described above in conjunction withhooks 302 a, 302 b. Note that smaller hooks 940 b are spaced axially(inwardly) of hooks 940 a as well as spaced axially with respect to eachother in the same manner as described with respect to hooks 740 b offilter 700 and illustrated in FIG. 20F showing the three differentdistances E1, E2 and E3 in the developed view. Other hook designs couldalternatively be provided, including the various hook embodimentsdescribed herein.

The tubular portion 918 is preferably in the form of a retrieval hook950 as described herein with respect to the other embodiments, andpreferably in the form of retrieval hook 290 of FIG. 13F. Otherretrieval structure can also be utilized.

Filters 700, 800 and 900 are preferably manufactured from a cut tube,preferably laser cut. Therefore, as in the other embodiments describedherein, terms such as interconnected, connected, joined, etc., are usedfor ease of description, it being understood that preferably theseportions are integral as they are preferably formed from a single tube.Also, mounting struts and filter struts used to describe the variousembodiments disclosed herein can be considered as mounting strut“portions” or “sections” and filter strut “portions” or “sections” ofthe same struts if the filter is formed integrally, e.g. from a cuttube.

The foregoing filters can be inserted through the femoral vein oralternatively through the internal jugular vein. It can be removed fromaccess through the internal jugular vein or femoral vein. Variousmethods can be used to remove the filter such as those described incommonly assigned application Ser. No. 09/911,097, filed Jul. 23, 2001,now published application 2002-0193827-A1, published Dec. 19, 2001, theentire contents of which is incorporated herein by reference, includingfor example, slotted hooks, graspers, etc. A recess or cutout can alsobe provided at the tubular end portions to receive a snare or otherdevice for removal. A hook 222 at tubular portion 220 is illustrated inthe embodiment of FIG. 13A and is configured to receive a snare. FIG.13B illustrates another embodiment of a hook. Hook 232 formed in tubularportion 230 forms a cutout 234 for receiving a snare or other removaldevice. The snare can surround and grasp both ears 235. However, the gap237 between the ears 235 also enables a retrieval snare to lie in thegap 237 to surround and grasp one of the two ears 235.

In the alternate embodiment of FIGS. 13C and 13D, hook 272 is similar tohook 232 of FIG. 13B in that it has two ears 275 with a gap 277therebetween. However it differs in that it has a bottom cutout 278formed between walls 279. It also differs in that surfaces 274 of ears275 are rounded and outer proximal walls 278 a angle outwardly(proximally) to curved peak 276 then angle inwardly (wall 278 b) toprovide a smoother transition into the retrieval sheath. Thus, twoangled transitions are provided.

In the alternate embodiment of FIG. 13E, to further enhance thetransition to facilitate withdrawal into the retrieval sheath, the sidewalls 284 extending into ears 285 of hook 282 angle inwardly toward thelongitudinal axis. Consequently, there are three angled transitions: 1)an angled transition in a first direction formed by angled walls 288 awhich angle proximally outwardly from the edge 285 a of ears 285 to thecurved peak 285 b (the proximal end of the hook is designated generallyby reference numeral 283); 2) an angled transition in a second directionformed by angled walls 288 b which angle distally outwardly from curvedpeak 285 b; and 3) an angled transition formed by walls 284 which angleproximally inwardly as walls 284 come closer together toward theproximal end. This results in a smoother transition into the retrievalsheath as it reduces the likelihood of the filter proximal end, i.e. thehook, being caught on the edge of the sheath—the angled edges whichcreate camming surface for all approaches of the filter (360 degreerange) will help the hook edges slide into the sheath.

FIGS. 13F and 13G illustrate another alternate embodiment of theretrieval hook of the present invention. This is the retrieval hookshown in conjunction with filter 301 of the embodiment of FIGS. 11D and11G. Hook 290 has a curved hook 292 at the proximalmost end. This hook292 is configured to receive a retrieval snare or other retrievaldevice. A portion of the wall of the hook 290 is cut out to expose theannular interior surface 294. That is, being formed from a laser cuttube, a wall portion is removed to expose curved inner wall surface 294.This annular interior surface 294 extends from radiused region 295 toproximalmost edge 296. The interior surface 294, for ease ofexplanation, can be considered to have an interior surface 294 a at theradiused region 295 and an interior surface 295 b at the hook 292. Theinterior surface 294 b accommodates a portion of a tubular snare sheath.That is, the outer wall of the snare sheath (tube) can partially fitwithin the cut out region 293. This enhances removal as the snare pullsthe filter hook into collinear arrangement with the sheath tube. Thiscan be appreciated by reference to FIGS. 13H-13J discussed below. Theradiused region 295, spaced axially (distal) from the hook 292, includesa radiused or curved edge defined by radiused side walls 297 a, 297 cand top wall 297 b. The angled side walls 297 a, 297 c form cammingsurfaces to direct the hook 290 and filter into the retrieval sheath.This can be appreciated by reference to FIGS. 13K-13N discussed below.

It should be appreciated, that the hook can be formed in other ways toprovide an interior annular surface to function in a similar manner assurface 294, i.e. to receive the snare tube.

It should be appreciated that any of the retrieval hooks can be usedwith any of the filters described herein.

In FIGS. 13H-13J, the snare approaches the retrieval hook 290 in theorientation shown. This results in a collinear arrangement. Morespecifically, the snare 502 is part of a retrieval system which includesa snare sheath or tube 504 through which the snare 502 extends. Thedistal wall 503 of snare sheath 504 provides for cinching of the snare502. The snare sheath 504 is inserted through retrieval sheath 510. Whenthe filter is pulled into the retrieval sheath 510 it is collapsed forremoval. As discussed above, preferably cold saline is injected duringthe removal process to cool the sheath to transition to a softermartensitic state to facilitate removal.

In the orientation shown, as snare 502 retracts the filter, the snaresheath 504 fits into the cut out region 293 as its outer wall conformsto the inner wall surface 294 b of hook 292. Thus, the hook 290 andsnare sheath 504 become substantially collinear as shown in FIG. 13I.This collinear arrangement facilitates retraction into the retrievalsheath 510 as it reduces the likelihood of a wall of the hook gettingcaught on the distal edge 512 of the retrieval sheath 510, thusproviding a smoother transition into the sheath as shown in FIG. 13J.

FIGS. 13K-13N illustrate the retrieval steps when the snare approachesfrom the opposite orientation of FIG. 13H, i.e. below the hook as viewedin the orientation of FIG. 13K. As the snare 502 retracts the filtertowards the sheath 510, the wall 297 b contacts the edge 512 ofretrieval sheath 510 and due to the radiused walls 297 a, 297 c(depending on the side of contact), the hook is cammed downwardly (inthe orientation of FIG. 13M) into the retrieval sheath 510 as shown inFIG. 13N. This provides a smooth transition into the retrieval sheath510 as it reduces the likelihood of the hook being caught on the sheathedge.

FIG. 12A illustrates another embodiment having a series of recesses 210along the length of the tubular portion 212. This enables the tubularportion 212 to be grasped at several locations along its length,facilitating grasping of the filter for removal. These multiple recessesor cutouts 210 are axially spaced as shown. In the embodiment of FIG.12B, the end of the tubular portion 240 has a series of axially spacedcutouts 242 which form a coil-like engagement structure. This engagementstructure provides multiple engagement areas for a retrieval (removal)device, such as a retrieval snare, for grasping the filter as the devicecan for instance be cinched in any of the spaces (formed by the cutouts)between the turns 246 in the helical coil. FIG. 12C shows a snare 300placed in one of the cutouts 242.

To facilitate removal of the filter from the vessel, cold saline can beinjected onto the implanted filter to change the temperature of thefilter to move it to a relatively softer condition to facilitate thefilter being drawn in to the retrieval sheath. That is, injection ofcold saline will cause the filter to approach its martensitic state,bringing the filter to a more flexible condition. The flexible conditionfacilitates the collapse and withdrawal of the filter into the retrievalsheath, by decreasing the frictional contact between the filter and theinner surface of the retrieval sheath.

A delivery system for the filter of the present invention is shown inFIGS. 17 and 18. The delivery system 600 includes a hub 602, a cartridge604 containing the filter, a pusher 606 and a wire 608 extending throughthe pusher 606. The wire 608 extends through the cartridge 604 andthrough the length of tube 603 to maintain a separation of the hooks,e.g. hooks 402 of filter 350 of FIG. 11G, during insertion of thedelivery system and delivery of the filter. The cartridge 604 isremovably attached to the hub 602, preferably by a snap-fit althoughother modes of attachment are also contemplated. The cartridgepreferably has markings (not shown) on the outer surface to indicate afemoral or jugular direction so the user knows the orientation to attachthe cartridge 604 to hub 602.

Once attached, advancement of the pusher 604 advances the filter fromthe cartridge and through tube 603 as the distal edge of the pusher 604abuts the proximal end of the filter, with the wire 608 (e.g., a Nitinolwire) preventing entanglement of the retention hooks. The wire 608 alsoprovides support (stability) for the pusher 604 as the pusher 604 isadvanced over the wire 608. The filter is forced out of the distal endof the tube, where it is no longer cooled by saline and is warmed bybody temperature to return toward its memorized configuration.

To enhance the retention of the cartridge 604 in the hub 602, a lockingmechanism can be provided such as the mechanism of FIG. 19. Thecartridge 604 has a pair of locking rails 612 a, 612 b, each including arespective recess 614 a, 614 b. The hub 602 contains a detent 620 asshown. When the cartridge 604 is inserted into the hub 602, the recess614 a of the locking rails 612 a is retained by the detent 620. Thislocks the cartridge 604 to the hub 602 during use, preventing unwantedseparation of the cartridge 604 from the hub 602. If access via thejugular artery instead of the femoral artery is desired, then thecartridge is inserted so that recess 614 b of rail 612 b engages detent620 of hub 602.

While the above description contains many specifics, those specificsshould not be construed as limitations on the scope of the disclosure,but merely as exemplifications of preferred embodiments thereof. Forexample, the filters can be inserted in other regions of the body. Also,any of the aforedescribed filters can have mounting sections of varyingthickness. The foregoing filters can be made of materials other thanshape memory material. Those skilled in the art will envision many otherpossible variations that are within the scope and spirit of thedisclosure as defined by the claims appended hereto.

What is claimed is:
 1. A vessel filter comprising a tubular region and aplurality of elongated filter struts extending initially linearlydistally from the tubular region and then angling radially outwardlyfrom a longitudinal axis of the filter to diverge, the plurality ofelongated filter struts including at least first, second and thirdelongated filter struts, the first elongated filter strut separatinginto diverging first and second connecting struts which extend therefromin different directions, the second elongated filter strut separatinginto diverging third and fourth connecting struts extending therefrom indifferent directions, the first and third connecting struts convergingat a first joining region to form a first four sided closed geometricshape and the second connecting strut converging at a second joiningregion with a fifth connecting strut diverging from the third elongatedfilter strut to form a second four sided closed geometric shape, thefirst and second geometric shapes formed in a filter region of thefilter, a transverse dimension at the joining regions of the connectingstruts being greater than a transverse dimension at the tubular region,and an elongated mounting strut extending from each of the joiningregions and being unconnected along their length.
 2. The vessel filterof claim 1, wherein the elongated mounting struts further comprise avessel engaging hook extending therefrom.
 3. The vessel filter of claim2, wherein the elongated mounting struts terminate in the vesselengaging hooks.
 4. The vessel filter of claim 1, wherein the vesselfilter has a midpoint, and a region wherein the first and secondelongated filter struts separate is proximal of the midpoint.
 5. Thevessel filter of claim 1, wherein the first and second closed geometricshapes are substantially diamond shaped.
 6. The vessel filter of claim1, wherein the tubular region has a cutout formed therein to form aretrieval hook.